Guideline 1.1 For non-text content, provide text
equivalents that serve the same purpose or convey the same information as the
non-text content, except when the sole purpose of the non-text content is to
create a specific sensory experience (for example, music and visual art) in
which case a text label or description is sufficient.
The text equivalent fulfills the same function as the author
intended for the non-text content (that is, it conveys all of the
intended information and achieves the same function as the non-text
content).
Exception:
If the purpose is to let users provide the text-equivalent (for
example, a spelling test) then the text-equivalent is not required.
Non-text content that is designed to create a
specific sensory experience (such as music without words or visual art)
has a text label or a text description explicitly associated with it.
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